Restructuring - Additional Information (Details) - USD ($)	3 Months Ended				9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 167,000	$ 193,000	$ 398,000	$ 139,000	$ 758,000	$ 1,898,000
2015 California manufacturing operations restructuring plan
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 0			$ 100,000	$ 0	$ 300,000